The groundwater is the largest freshwater reservoir on Earth in liquid form. These waters though are not isolated from the rest of the freshwater, but instead they are connected with the streams, thus they affect them heavily.
The groundwater has been heavily used in the last century, and it has been depleted. The depletion of the groundwater has been the result of over usage, or to put it simple, more water has been extracted than what naturally is replenished.
This has been causing more and more problems. Apart from the groundwater resources getting depleted and than be unusable, the depletion of their water has resulted in lowering of the level of water of the streams, as the streams have been receiving less and less water. Also, because there is much less water and it mixes with lot of ground and rocks, the water quality has been becoming worse and worse, and if this trend continues it can have devastating effects.
Ground water pumping can alter how water moves between aquifer and a stream, or lake by either intercepting groundwater flow that discharges into the surface-water body under natural conditions, or by increasing the rate of water movement from the surface-water body into an aquifer.
